The present invention, although applicable towards various types of golf club heads, may generally be most applicable towards wedge type golf club heads due to their unique need to utilize the grooves for spin purposes. Wedge type golf club heads, more commonly known as wedges, are a particular type of golf club that generally has a high loft angle. These higher lofted wedges tend to be precision instruments that allow a golfer to dial in short range golf shots with improved trajectory, improved accuracy, and improved control. This increased loft angle in wedges generally yield a golf shot with a higher trajectory because the impact surface on the golf ball is not perpendicular to the trajectory of the club head; rather the golf ball interacts with the wedge at an inclination closely resembling the actual loft angle of the wedge itself. This inclination generally causes the golf ball to move up along the inclination of the wedge when struck by the wedge type golf club head, creating a backward rotation of the golf ball as it leaves the wedge club face. This backwards rotation of the golf ball may generally be known as “backspin” within the golf industry; and this backspin is desirable in helping improve trajectory, accuracy, and control of a golf shot using a wedge type golf club head.
Backspin helps improve trajectory, accuracy, and control of a golf shot by giving the golf ball a gyroscopic effect, which stabilizes trajectory, hence increasing accuracy. Moreover, backspin also serves to increase control of a golf shot as backspin minimizes the roll of a golf ball after landing, allowing a more predictability.
One of the ways to generate this desirable backspin is to increase the coefficient of friction between the wedge type golf club head and the golf ball. In order to achieve this higher coefficient of friction, wedge type golf club heads generally have horizontal grooves at the striking surface to catch the golf ball as it leaves the face of the club. It is well known in the art that the shape, depth, width, and geometry of the grooves on the striking surface of a wedge have a direct correlation with the amount of backspin on a golf ball.
In an attempt to increase the performance characteristics of a wedge type golf club, the grooves are getting sharper and more aggressive and creating more backspin. However, it is commonly known that these sharper and more aggressive grooves are more prone to wear over time. This wear is often caused by erosion that results from repeated impact between a golf ball and the wedge type golf club head. Moreover, this erosion process can be intensified when various other harsh abrasives such as soil and sand that could get caught between the wedge type golf club and a golf ball. Hence it can be seen that the wear and tear on the horizontal grooves of a wedge type golf club head may generally decrease the amount of backspin on a wedge type golf club head over time, leading to a decrease in its performance characteristics.
Many methods have been used to extend the life of a wedge type golf club head's grooves as well as the maintaining the striking face all while creating or maintaining a high coefficient of friction. Hard surfacing compounds have been plasma sprayed on the striking surface as one method to maintain performance and durability of the grooves on the striking surface of the wedge type golf club head. Alternatively, ball striking surface have also been carburized and nitrided in the past to minimize the wear and tear as well as creating a desired patina or coloration. Ceramic substances have also been flamed sprayed on the ball striking surface in the past to improve wear resistance and to create a desired coloration. Ball striking surfaces have also been sandblasted in addition to ion implantation techniques.
U.S. Pat. No. 4,768,787 to Shira titled Golf Club Including High Friction Striking Face ('787 patent), although more particularly directed towards an iron type golf club head, provides a more detailed example of a golf club with an improved striking surface wherein the striking surface has hard particles embedded therein with portions of the particles protruding above the surface so as to provide greater frictional grip between the golf ball striking surface and the golf ball. More specifically, the '787 patent discloses a club wherein the hard particles project or protrude slightly above the ball striking surface of the “iron” head and create friction between the club and the golf ball. Over an extended period of service, the matrix material will wear more rapidly than the hard particles, and the hard particles will continue to perform their friction creating function.
These approaches, although capable of providing a striking surface that has increase hardness and friction, require additional manufacturing processes that may be extensive and burdensome. Additionally, these approaches do not take advantage of the inherent material properties of a wedge type golf club head that is generally made out of carbon steel. Most importantly, methods such as the utilization hardened particles do not provide an even surface on the striking surface of the wedge, sacrificing performance properties in exchange for durability.
As indicated above, most of the modern wedges may generally be comprised of a carbon steel material that may have certain materials properties that lends itself well to heat transformation surface transformation. All of the above mentioned approaches to extending the performance characteristics of a wedge type golf club head do not utilize or take advantage of the inherent physical properties of the material from which the wedge type golf club head is made from. Martensitic crystalline layer may generally be achieved by heat treating the surface of a wedge that is comprised of carbon steel and rapidly quenching the wedge in a fluid to change the material properties of the heat treated surface.
Hence, it can be seen that there is a need in the field for a golf club head that has increased hardness on the striking surface. More specifically, there is a need for a wedge type golf club head that is capable of achieving an increased hardness on the striking surface without the need for additional surface treatments. Even more specifically, there is a need in the field for a wedge type golf club that utilizes the inherent crystalline composition structure of carbon steel to create a martensitic layer for improved hardness in the striking area.